"Hi, I am looking for an advanced open source media player for Linux, something like JetAudio using which I can easily navigate through the media by arrow keys. mplayer is not bad, I have tested that in text mode, but when you use arrow keys, it jumps 10 seconds. It would be nice if you could navigate in a more subtle way (little back and forth jumps less than 10 seconds). Probably there are other players out there in open source community. Please share your ideas and experience. Thanks a lot, Mehdi"

Another nod for VLC. Not only is it open source, it is also cross-platform, working on both Linux and Windows.

For audio-only players, I use Banshee. Its a good, lightweight player that Just Works, though its library display is minimalistic (I wish I could drill down by genre, for example). I have also used Exaile, which I believe is also open-source. It, too, is a good, reasonably-featured player with a minimalist look and feel. Amarok is a good player as well, though it's pretty heavy-weight and has a lot of dependencies, particularly for non-KDE distros.